[diesel 4ever]

Being not especially good with electronic engineering (I can use a multimeter fine and understand the basics), I am wondering if I could install an ammeter or ohmmeter into the circuit of my push button glow plug system in order to monitor the overall "health" of my glow plug system. Might that give me an idea if I have a glow plug out or some that are beginning to get old?

 

[WhiteGardens]

I really don't know if this would work or not, and how to begin installing it.

New Mini 650 Ohm 500uA Panel Meter Gauge - eBay (item 260301994854 end time Jan-15-09 13:20:36 PST)

 

[CDX825]

You would need a shunt with that meter. Not sure on the size though. You need a shunt and meter combo that can handle at least 200 amps.

 

[BuilderBob]

Remember that you need to confirm that 8 wires are carring amps to 8 GP's. Knowing that voltage is present is not enough, it does not confirm that GP's are conducting. You don't need to know how much current, only that all 8 GP's are conducting
An amp meter to measure total GP current is not sufficent as current is dependant on voltage, and the voltage will vary depending on many factors, such as battery condition, battery temperature. Current will vary and is not repeatable.

I am good at Electrical Engineering, and this is a thorny issue, but have hashed it over mentally. I have not needed this because my truck works as designed.

 

[Plywood]

A handheld ohmmeter uses a very small voltage to measure resistance.
If you apply 12V, as it says below, you would have to have a meter that can handle that much amperage.
Unfortunately, there isn't enough info on that e-bay listing to know, as Mr Gardens says, how it works, or if it will work.
I think that an amp meter would give you the "idea" of their health as you say, but a 200or so amp meter? where and how expensive? and you would have to run a "big" wire from your GP relay to the meter in the cab, and really it isn't safe, which is why there is a relay.

That being said, here is the only thing I can fathom working.

Use a three position switch. On-Off-Momentary On
Find an ohmmeter that steps the 12 volts down to a tiny voltage, or the right combination of transformer and meter, so that when you are reading the resistance, you are not really energizing the GPs.
Hook the momentary position on the switch to "fire" the GPs.
For the "On" position, you would go from battery to meter to "On" position of switch, and then to the GPs.
This way when you "fire" the GPs you would not fry the meter, and when you switch to the meter, the glow plugs will not be energized with 12 volts.
I suppose you could wire in a handheld meter, you would just have to have batteries in it.

To answer your question, no, I am not normally such a nerd.

 

[WhiteGardens]

To answer your question, no, I am not normally such a nerd.

Ya right.:lol:

Mr Gardens says......,

That makes me feel old.

I had no idea if that listing would work or not. I would think you would need a meter on every glow plug in order to have any idea of what was going on. Or, An 8 position switch and one meter to switch from every glow plug.

The only other thing I can think of measuring is the resistance from a solid state controller, just to keep track if you had a failure somewhere.

 

[CDX825]

With a shunt you would not have to run any heavy wires inside the cab. Only two smaller wires to the meter. The shunt caries most of the current. Still as noted before amperage will change based on voltage and temp of the plugs. This would give you a general idea though.

 

[BuilderBob]

With a shunt you would not have to run any heavy wires inside the cab. Only two smaller wires to the meter. The shunt caries most of the current. Still as noted before amperage will change based on voltage and temp of the plugs. This would give you a general idea though.

You are correct, but
with one current shunt, you would measure current for the complete circuit, not good, as it will vary, as you have noted.

Eight current shunts will be better, each to measure the individual GP's. But still not what we need.

Remember that you only want to confirm that current is flowing to each of the 8 GP's. It does not matter how much current, only that current is flowing in each individual GP.
With that in mind, if each GP wire could be outfitted with a current sensor, and that current sensor were to cause a light to illuminate when current to the GP is flowing, then have 8 light on the dash, that you would observe when starting.

Start your work on the current sensor, and interface to an LED. Sounds easy, but it is not.

Best of Luck

 

[CDX825]

I was thinking shunt for the whole circuit but its just not practical as you mentioned its going to fluctuate.

 

[agnem]

An ameter would be best, but you could also get a feel with a voltmeter. If you connected it to your #1 or #2 glow plug connector, you will be able to see the voltage drop through the harness. A healthy glow plug system will actually suck the voltage down to about 7 volts at that test point when first turned on. As they heat, you will see the voltage go up. As glow plugs die off, or resistance enters the circuit through other means, you will see the starting voltage get higher. Through repetative observation, you would come to know what is normal, and be able to identify what is not.

 

[maxdiesel]

I picked up 2 12v panel lights I was thinking about installing one right and one left on the glow plug harness. My thinking is that the bulbs will go dim or bright depending on what the glow plugs are doing. I haven't put it in yet so I can't say how well it works but I'm going to give it a shot.